That’s speculation again. And I’m not sure what’s cause and what is effect. This is intertwined. We’d need someone to study this and not link studies from 2019 about oxytocine.

And concerning the birth rates: Earth’s population is in fact predicted to grow until 2060 or 2070. As a species we don’t have any issue with declining birth rates. If people say things like that, they mean western societies (and Japan and Korea) have an issue with reproduction. And we won’t have that many white babies. We’re gonna have enough babies, though. More than enough to grow to 10B people when population growth maybe peaks.